Methods of controlling the load of a light emitting diode (LED) are generally classified into three types of methods, including resistance methods, linear control methods and switching control methods. Of the three, linear control methods and switching control methods are methods of supplying a constant current.
A switching control method is capable of maintaining a constant brightness regardless of voltage fluctuation and is flexible regarding design changes to deal with a quantity and current change of an LED. However, switching control methods include features of a complicated circuit, a high design cost and weak characteristics in response to electromagnetic waves.
A linear control method is capable of maintaining the load 100 of an LED at a constant brightness in spite of voltage fluctuation, is excellent in terms of power stability and reliability and has a simple circuit structure. However, linear control methods are disadvantageous in that a current that can be supplied for each LED package is fixed and a sufficient area of a printed circuit board (PCB) is required due to large amount of heat generation.
Therefore, a need for a control apparatus capable of resolving the heat generation problem and stably supplying a current is unmet.